Analogue private communication based on hybrid chaotic systems with delays

International audienceSince most of private communication schemes based on chaotic synchronization are not robust again plain-texts attacks, the introduction of delays in the schemes can be regarded as an efficient method to improve the security degree with respect to such attack. As an extension of our recent work, this paper proposes a new analogue private communication scheme based on hybrid chaotic systems with delays. The proposed scheme is based on the notation of weakly left invertibility of switched systems, and an illustrative example is given for the purpose of highlighting the feasibility of the proposed method

Robust reconstruction of the discrete state for a class of nonlinear uncertain switched systems

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Discrete breathers in classical spin lattices

Discrete breathers (nonlinear localised modes) have been shown to exist in various nonlinear Hamiltonian lattice systems. In the present paper we study the dynamics of classical spins interacting via Heisenberg exchange on spatial $d$-dimensional lattices (with and without the presence of single-ion anisotropy). We show that discrete breathers exist for cases when the continuum theory does not allow for their presence (easy-axis ferromagnets with anisotropic exchange and easy-plane ferromagnets). We prove the existence of localised excitations using the implicit function theorem and obtain necessary conditions for their existence. The most interesting case is the easy-plane one which yields excitations with locally tilted magnetisation. There is no continuum analogue for such a solution and there exists an energy threshold for it, which we have estimated analytically. We support our analytical results with numerical high-precision computations, including also a stability analysis for the excitations.Comment: 15 pages, 12 figure

Using discrete-time hyperchaotic-based asymmetric encryption and decryption keys for secure signal transmission

In this paper, a framework for the synchronization of two non-identical discrete-time hyperchaotic systems, namely the 3D Baier-Klein and the 3D Hitzel-Zele maps, based on the use of hybrid output feedback concept and aggregation techniques, is employed to design a two-channel secure communication system. New sufficient conditions for synchronization are obtained by the use of Borne and Gentina practical criterion for stabilization study associated to the forced arrow form matrix for system description. The efficiency of the proposed approach to confidentially recover the transmitted message signal is shown via an application to the hyperchaotic Baier-Klein and Hitzel-Zele systems, considered as generators of asymmetric encryption and decryption keys

Nonlinear discrete-time systems with delayed control: a reduction

In this work, the notion of reduction is introduced for discrete-time nonlinear input-delayed systems. The retarded dynamics is reduced to a new system which is free of delays and equivalent (in terms of stabilizability) to the original one. Different stabilizing strategies are proposed over the reduced model. Connections with existing predictor-based methods are discussed. The methodology is also worked out over particular classes of time-delay systems as sampled-data dynamics affected by an entire input delay

On switched Hamiltonian systems

In this paper we study the well-posedness and stability of a class of switched linear passive systems. Instrumental in our approach is the result, also of interest in its own right, that any linear passive input-state-output system with strictly positive storage function can be written as a port-Hamiltonian system